1. Field of the Invention
This invention relates to a novel quinizarin compound, a method for the production thereof, a dye formed of the compound, and an electrophotographic color toner composition, a thermal-transfer recording sheet, an optical recording medium, a color filter, and an ink jet grade ink composition severally containing the compound.
The novel quinizarin type compound of this invention exhibits absorption in an orange-red-blue-green-near infrared region of 480 nm to 850 nm in wavelength, manifests outstanding solubility, and excels in resistance to light or heat. In the field of optoelectronic data, the novel quinizarin type compound manifests an excellent effect as display materials or recording materials exhibiting absorption in the visible region or near infrared region when it is used in a thermal-transfer dye, an ink jet grade ink, a color separation filter for a camera tube, a liquid crystal display grade color filter, an optical color filter, a color toner, a bar code grade ink for preventing fake, a guest-host type liquid crystal display grade dichroic dye, a polarizer grade dichroic dye, an optical recording media suitable for compact disk, etc. The effect so manifested particularly gains in prominence when this compound is used in a magenta type or cyan type dye.
Further, as a high-quality coloring agent of excellent solubility and high fastness fit for the orange-red-blue-green region, the quinizarin type compound of this invention manifests an ideal effect when it is used in dyes for fibers, paints for automobiles, paints for building materials, coloring agents for printing plates, writing inks, coloring agents for glass flakes, and coloring agents for spectacle lenses.
2. Description of the Prior Art
In recent years, the functionalities of the organic dye manifested in the field of optoelectronic data recording have been attracting attention of the industry as the trend of the field toward impartation of colors to the data display images or their hard copies has been gaining in impetus. As respects the display materials or recording materials suitable for this trend, the necessity for developing the so-called visible light absorption dye such as, for example, a thermal-transfer dye, an ink jet grade ink, a color separation filter for a camera tube, a liquid crystal display grade color filter, an optical color filter, a color toner, a bar code grade ink for preventing fake, a guest-host type liquid crystal display grade dichroic dye, and a polarizer grade dichroic dye which exhibit an absorption in the visible region has been finding growing recognition.
Particularly, in recent years, applications which handle electronic images including computer graphics have been suddenly increasing. As a result, the desirability of having such electronic images as TV images of video movies and electronic still cameras recorded as color hard copies has been finding growing recognition.
Among other methods which are available for the purpose of this recording, the so-called thermal-transfer recording method which comprises using a thermal transfer sheet formed by coating a substrate sheet with a thermal-transfer grade dye, heating selectively the sheet with a thermosensitive head, and transferring the molten dye onto a recording paper dyable with the molten dye has been attracting attention as an important recording method capable of producing a full-color image excellent in repeatability of gradient and color.
Generally, the primary colors of yellow, magenta, and cyan are used for these thermal transfer sheets. Very few of the dyes heretofore proposed, however, satisfy all the conditions necessary for the thermal-transfer recording, namely (1) color tone, (2) solubility in or compatibility with an ink solvent and an ink binder resin, (3) resistance to heat, (4) transferability, and (5) lightfastness. Thus, the appearance of a dye satisfying the optimum conditions for the operation of the thermal-transfer recording has been longed for.
Among other compounds, the anthraquinone type compounds which are inherently stable to resist against light, heat, and temperature and excellent in fastness have been being studied from numerous angles for the purpose of adapting them to be controlled to an absorption wavelength necessary for magenta dyes and cyan dyes and to be rendered soluble in a solvent or a resin as required by intended applications.
For example, JP-A-60-122, 192, JP-A-60-131,293, JP-A-60-159,091, JP-A-61-227,093, JP-A-60-253,595, JP-A-62-25,092, JP-A-62-97,886, JP-A-63-288,787, JP-A-63-288,788, JP-A-63-288,789, JP-A-01-174,490, JP-A-04-21,490, etc. disclose magenta dyes which result from introducing various functional groups at the 2 position into the 1-amino-4-hydroxy-anthraquinone compound. Though some of them possess solubility, they are invariably deficient in absorption wavelength or lightfastness.
Further, JP-A-59-227,948, JP-A-60-31,559, JP-A-60-53,563, JP-A-60-122,192, JP-A-60-131,292, JP-A-60-131,294, JP-A-60-151,097, JP-A-60-172,591, JP-A-61-57,391, JP-A-61-193,887, JP-A-61-255,897, JP-A-62-138,291, JP-A-01-178,495, JP-A-01-221,287, JP-A-01-255,594, JP-A-01-258,995, JP-A-01-258,996, JP-A-02-9,685, JP-A-02-43,093, JP-A-02-132,462, JP-A-02-175,293, JP-A-04-122,695, JP-A-04-270,689, etc. disclose anthraquinone type cyan dyes which have amino group, alkylamino group, allylamino group, and various functional groups introduced therein. Though some of these dyes possess solubility, they are invariably deficient in absorption wavelength or lightfastness.
The electrophotography generally produces a visible image by a procedure which comprises forming an electric latent image of static charge on a photoelectroconductive sensitive material by charging or exposure to light, then developing this electric latent image with a toner, optionally transferring the resultant toner image onto a transfer paper, and fixing the toner image by application of heat or application of pressure. For the visible image, generally the toner which is produced by dispersing a black coloring agent such as carbon black in a binder resin is mostly used. The sudden increase of the applications which deal with electronic images including computer graphics has been even urging the electromicrography to promote the impartation of colors to the electronic images. Thus, the practice of producing color toners having various dyes and/or pigments of yellow, magenta and cyan, dissolved or dispersed in a binder resin has been prevailing.
Generally, the full-color toner has been heretofore produced by melting a binder resin and a coloring agent, kneading the molten mixture, pulverizing the resultant mixture, and classifying the produced powder and separating a powder having a prescribed grain size distribution. In this case, a pigment is generally used as a coloring agent. The color imparted by the pigment is at a disadvantage in being deficient in transparency because the pigment as a coloring agent is merely dispersed in the binder resin. Particularly when an electronic image is to be formed as on a transparent sheet for use with an overhead projector, the projected image is dim and turbid. The problem of poor transparency may be solved to a certain extent by decreasing the grain size of the pigment particles to the order of sub-microns. The pulverization of the pigment to the order of sub-microns is difficult to attain. Further the pulverized pigment is required to be uniformly dispersed finely in the binder resin. This uniform dispersion is extremely difficult to attain.
Numerous studies have been being continued in search of a dye which exhibits solubility in a binder resin. The use of such a dye as a coloring agent, however, has the problem that it goes chiefly to degrade the lightfastness of the produced toner. Thus, numerous studies are now under way regarding the usability in the toner of a dye which exhibits high compatibility with a binder resin and abounds in lightfastness. For example, the anthraquinone type cyan dyes are disclosed in JP-A-01-237,667, JP-A-01-284,865, JP-A-02-47,668, JP-A-02-110,573, JP-A-02-132,462, JP-A-03-87,754, JP-A-05-107,812, etc. None of them, however, satisfies all the conditions of transparency, color tone, and lightfastness.
In recent years, such optical recording media as compact discs, laser discs, optical memory discs, and optical cards which use a semiconductor laser as a light source have been being developed actively. Particularly, CD, PHOTO-CD, and CD-ROM are now copiously utilized as digital recording media of high capacity and rapid access for the storage and regeneration of voices, images, and code data. These systems invariably are in need of so-called near infrared absorption dyes which are sensitive to the semiconductor laser. These dyes are desired to possess excellent characteristics.
The basic characteristics which are required of such a dye for use in an optical recording medium include, for example, (1) that the dye is controlled to an absorption wavelength which is required for an intended application, (2) that from the practical point of view, the dye is applicable to a surface by a method which converts the dye into a thin film without using such a complicated step as vacuum deposition or dispersion in a resin, namely a method resorting as to a spin coat and enjoying convenience and excelling in productivity, and is excellent in solubility in a solvent incapable of corroding a substrate, (3) that the dye possesses high reflectance, (4) that the dye excels in resistance to heat and to light, (5) that the dye exhibits high sensitivity, and (6) that the dye as a compound excels in economy in association with a process for production.
Optical recording media using organic dyes which have been developed in recent years with a view to satisfying these characteristics have been studied. In this respect, such organic dyes as phthalocyanine dyes, polymethine dyes, squalium dyes, and anthraquinone dyes have been proposed. None of the dyes heretofore proposed, however, satisfies all the characteristics mentioned above.
JP-A-58-169,152, JP-A-62-21,584, and JP-A-63-102,988, for example, disclose methods which use anthraquinone compounds as dyes. These compounds, however, cannot be used practically because they are particularly deficient in lightfastness.
The color filter is generally constructed by repeating sequential superposition of fine colored picture elements in the form of thin films tinted in a plurality of colors on a substrate such as glass, plastic, camera element, or thin-film transistor and optionally further depositing a protective film thereon. Various methods have been proposed for the formation of such colored picture elements as mentioned above. For example, photolithographic methods, printing methods, electrodeposition methods, and vacuum deposition methods have been developed and adopted for practical use.
The color filters which are produced as described above are broadly divided under those of the class using the three primary colors of red, green, and blue and those of the class using the complementary colors of cyan, yellow, and magenta or the combination of two of these complementary colors with a transparent layer. In either case, it goes without saying that the spectral characteristics of a given color filter discriminate between acceptability and rejectability of the repeatability of color of the color liquid crystal display and the color grade solid camera element. Attempts has been made to develop dyes, pigments, or the combinations thereof which permit production of color filters possessing excellent spectral characteristics.
The dyes, pigments, and combinations thereof which have been developed heretofore, however, are at a disadvantage in being deficient in transparency and lightfastness and incapable of producing desired color tones or manifesting ample repeatability.
The ink jet grade inks in many cases provide critical print characteristics. To be specific, water-based ink jet grade inks generally manifest no affinity for paper and exhibit only a poor ability to permeate in a paper or dry in a paper. On the contrary, oil-based inks exhibit affinity for paper and are nevertheless at a disadvantage in being deficient in surface tension and consequently liable to form unduly large ink dots and impair the print quality. In contrast thereto, solid or semi-solid type inks are characterized by being capable of producing prints of excellent contrast and have prospects of bright future. None of the dyes or pigments which are available for solid or semi-solid type inks, however, satisfies the two factors of lightfastness and color tone at the same time.
An object of this invention, therefore, is to provide a novel quinizarin compound, a method for the production thereof, a dye formed of the compound, and an electrographic grade color toner composition, a thermal-transfer recording sheet, an optical recording medium, a color filter, and an ink jet grade ink composition severally containing the compound.
Another object of this invention is to provide a novel quinizarin type compound which is one species of anthraquinone type compounds and which constitutes a visible light absorption material permitting control to an absorption wavelength fit for an intended application within the range of absorption wavelength from 480 to 700 nm and excelling in solubility in a solvent of resin used in the intended application and in lightfastness as well.
A further object of this invention is to provide a method for producing the quinizarin type compound with high efficiency.
Still another object of this invention is to provide a dye formed of the compound mentioned above and used as for a visible light absorption material.
Yet another object of this invention is to provide an electrophotographic grade color toner composition which, owing to the use of the dye possessing solubility in or miscibility with a binder resin, serves as a magenta and/or cyan color toner satisfying all the factors of transparency, color tone, and lightfastness.
Another object of this invention is to provide a dye satisfying all the conditions of (1) color tone, (2) solubility in or compatibility with an ink solvent and an ink grade binder resin, (3) resistance to heat, (4) transferability, and (5) lightfastness which are necessary for the magenta and/or cyan dye in a thermal-transfer recording sheet, and a thermal-transfer recording sheet containing the dye.
Yet another object of this invention is to provide a novel optical recording medium, particularly a CD-oriented optical recording medium which uses a laser with a wavelength of 780 nm or 680 nm, which excels in absorption wavelength, sensitivity, reflectance, and lightfastness owing to the use of a novel anthraquinone compound permitting control to an absorption wavelength fit for an intended application within the range of absorption wavelength of from 600 to 850 nm, excelling in solubility in a solvent such as, for example, an alcoholic solvent fit for the intended application, and abounding in lightfastness and resistance to heat.
Another object of this invention is to provide a color filter exhibiting excellent lightfastness, showing no turbidity, diffusing sensation of transparency, and excelling further in terms of color tone.
Still another object of this invention is to provide an ink ideal contrast and production of recorded images excelling in lightfastness and in color tone as well.